Macbook Pro 13 Hard Drive Upgrade??

Im thinking about buying a refurbished or new "13" macbook pro but i want to upgrade the hard drive to possibly 500gb. My concern is, if i do this myself will this jeopardize my apple care warranty? Has anyone ever done this with their and had a problem? Is this an easy processes swapping out hard drives? Whats the best way on upgrading the hard drive? Thanks.

MacRumors attracts a broad audience
of both consumers and professionals interested in
the latest technologies and products. We also boast an active community focused on
purchasing decisions and technical aspects of the iPhone, iPod, iPad, and Mac platforms.